Inspection instrument

ABSTRACT

An observation device for inspecting elongated cavities is attached to the outer end of a cable made of pneumatic tubes and electrical conductors encased in a flexible sheath. The cable passes through a sleeve attached in an inflatable support that curves through an arc of approximately 90*, so that it enters the base of the inflatable support and emerges through the top thereof. The cable is attached to a control box containing connectors to a pressurized source of gas, a source of electrical power, and control means therefor. A series of inflatable braces concentrically surrounds the cable for supporting it in the center of the cavity to be inspected, each brace being inflatable through a pneumatic tube leading from the source of gas. The protective sheath of the cable is inflatable to impart rigidity when in use, and also to surround the pneumatic tubes with the same pressure as their interiors, so that wall thicknesses thereof may be minimized for compactness when stored.

McCullough et a1.

Dec. 3, 1974 INSPECTION INSTRUMENT Inventors: Edward E. McCullough,Brigham City; Kerry G. Zundel, Tremonton; La Ron D. Binggeli, Logan, allof Utah Thiokol Corporation, Bristol, Pa.

Assignee:

[22] Filed: Oct. 9, 1973 [21] App]. No.: 404,522

[52] US. Cl 178/7.l, 178/DIG. 1, 178/D1G. 30,

[51] Int. Cl. H04n 7/18 [58] Field of Search 1 78/DIG. 1, DIG. 30, 7.81,

[56] References Cited UNITED STATES PATENTS 3.329959 7/1967 McCormac 4.356/241 3,399,614 9/1968 Fischer l78/7.8l 3,609,236 9/1971 Hellman178/D1G. 1 3,689,695 9/1972 Rosenfield.... 178/7.81 3,764,736 10/1973Kosky i78/DIG. 1

Primary Examiner-Howard W. Britton Assistant Examiner-Michael A.Masinick Attorney, Agent, or Firm-Edward E. McCullough [5 7] ABSTRACT Anobservation device for inspecting elongated cavities is attached to theouter end of a cable made of pneumatic tubes and electrical conductorsencased in a flexible sheath. The cable passes through a sleeve attachedin an inflatable support that curves through an arc of approximately 90,so that it enters the base of the inflatable support and emerges throughthe top thereof. The cable is attached to a control box containingconnectors to a pressurized source of gas, a source of electrical power,and control means there for. A series of inflatable bracesconcentrically surrounds the cable for supporting it in the center ofthe cavity to be inspected, each brace being inflatable through apneumatic tube leading from the source of gas. The protective sheath ofthe cable is inflatable to impart rigidity when in use, and also tosurround the pneumatic tubes with the same pressure as their interiors,so that wall thicknesses thereof may be minimized for compactness whenstored.

10 Claims, 7 Drawing Figures INSPECTION INSTRUMENT This inventionrelates broadly to inspection devices, and more specifically to thosethat must be very portable and extensible in one direction forinspecting elongated cavities. The invention herein described was madein the .course of or under Contract AF 04(694)-926 with the U.S. AirForce.

Sometimes it is necessary to inspect an elongated cavity in asubstantially stationary object wherein the amount of room at theentrance to the cavity is restricted, so that the inspection instrumentmust be very compact and extensible to many times its storable length.An example of this is an experimental solid propellant rocket having acentral bore in the propellant. When experimental propellant is used insuch a rocket, it must be inspected periodically to assure thatundesirable effects, such as cracking, have not occurred as a result ofaging. Such an effect must be known before the rocket is fired, becausethe greatly increased burning surface created by the fractures can makethe rocket potentially dangerous. If the rocket is of a type having aplurality of thrust nozzles and an axial cavity in the propellant, anyinspection device that is supported outside such a rocket motor wouldhave to enter one of the nozzles and then execute two substantially 90turns in order to enter the axial cavity. Inspection of other types ofsolid propellant rocket motors having single nozzles also is usuallyvery difficult without removing the motor from itsstorage place.

SUMMARY OF THE INVENTION The present invention, which satisfies thisneed, is an inspection instrument havingan observing means supported onthe outer end of a cable thatcomprises a plurality of pneumatic tubesand electrical conductors encased in a flexible. sheath. This cablepasses through a sleeve, one end. of which enters an inflatable supportat its base, curves through-about 90, and penetrates the is. imparted tothe cable by inflating its sheath. Since this eliminates stress on thepneumatic tubes of the cable, their walls can be of minimal thicknessfor compactness when stored. Orientation and other operations of theobservation means are accomplished by appropriate well-known devices.

Objects of the invention are to provide an instrument for inspectingbores that is very portable; convenient to use; and that will not damagethe propellant inside the rocket motor. Important features of theinvention are that it is simple in construction, easy to manufacture,and inexpensive to make.

Other objects, features, and advantages of the invention will becomeapparent as the following description is read with reference to theaccompanying drawings,

wherein the same parts are designated with the same numbersthroughoutthe disclosure.

top of the inflatable support. The support is a hollow cone made of twoparallel layers of flexible material spaced apart by fibers anchored inthe layers or sheets, the parallel sheets being sealed at their edges toenclose an annular, conical volume which is to be inflated. The controlend of the cable is fastened to a control box that contains connectorsto a source of electrical power and to a source of pressurized gas. Thisbox alsocontains switches, valves, or other control means for regulatingthe flow of electrical power and gas to the cable. A series of annular,inflatable braces of nonelastic, thin, flexible material isconcentrically fixed to the cable and each is inflatable via one of thepneumatic tubes. The inflatable support maybe anchored to' the rocket orto some other stationary part by means of a strap. I I

When a rocket having a pluralityof nozzles and a central cavity-is to beinspected, the inflatable support is centered inside the aft closure,anchored to the rocket by means of a strap, and inflated. Gas is thenmeteredv into the pneumatic tube that communicates with the interior ofthe inflatable brace nearest the free end of the cable and outside theinflatable support. The desired height of .the observing device in thecavity is achieved simply by threading the cable through the sleeve, andthe inflatable braces may be inflated serially DESCRIPTION OF THEDRAWINGS FIG. 1 is a longitudinal section of a typical solidpropellantrocket motor with theinvention installed therein;

FIG. 2 is a top view of the control box;

FIG. 3 is a cross section of the'control box FIG. 4 is a side elevationof the control box, showing the cable connector;

FIG. 5 is a perspective detail showing both parts of the cableconnector; 7

FIG. 6 is a perspective detail of a typical valve; and

FIG. 7 is a side elevation ofv the camera and associated devices fororienting it as desired.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, theinvention hasa cable 10 having an outer sheath 11 that encloses aplurality of pneumatic tubes 12 and electrical conductors 13. Each ofthe pneumatic tubes 12 leads from a bottle 14 of pressurized gas, orother source of gas, to a specific, inflatable brace lS. One of themconnects the source of gas 14 with the inflatable base or support 26.Each inflatable brace 15 is annular, concentrically surrounding thecable 10. It is essentially disk shaped and is somewhat thickened at thecenter toprevent buckling.

A control box 16 (FIGS. 2, 3, and 4) has a cavity 17 to receive the gasbottle 14. A threaded orifice 18 may engage threads on the end of thebottle 14, and a puncture point 19 ruptures a diaphragm, not shown, inthe end of the bottle 14, when the threads have engaged sufficiently toform a gastight seal. A main duct 20 leads from the threaded orifice 18to a plurality of branch ducts 21, each of which connects at its otherend, via a connector 22 (See FIG. 5) to a selected tube 12. Intermediateeach branch duct 21 is a valve 23 and a flow meter 24 ..A-detail of avalve 23 is shown in FIG. 6. It has a through passage 23a that isalignable with a branch duct 21 in open position and a bleed orifice 23balignable with a branch duct 21 when an associated device is to bedeflated. In either case, the valve .memher 230 must be pressed againstthe spring 23d. Each of the inflatable braces 15 is made of a thin,flexible material that is nonelastic'so that it has a fixed form whenfully inflated, and, further, has fibers 15a passing between oppositewalls to promote dimensional stability. s

The cable passes through a curved sleeve 25 that is fixed in a base orsupport 26 having the form of a hollow cone. This hollow cone is made oftwo parallel sheets 27 of thin, flexible material that is nonelastic.They are sealed together at their top and bottom edges to form a closed,annular, inflatable space. Dimensional stability of the base 26 isfurther insured by a multiplicity of fibers 28 that extend between thesheets 27 and are embedded therein at their ends. Material of thisnature is commercially available. A buckle equipped strap 29 is fastenedto the base of the support 26, whereby the support 26 may be centeredand firmly attached inside the cavity 30 of the rocket motor 31. Thecontrol box 16 also has electrical controls 32 attachable to a source ofelectric power, to the television camera 33, and to its horizontalelectrical step motor 34 and vertical actuator 35, respectively. Theelectrical conductors are not shown. The television camera 33 and itsstep motor 34 and actuator 35 are of types well known in the art and arecommercially available.-

The invention may be practiced by first threading one end of the strapthrough one nozzle 36 of the rocket motor 31 and allowing it to slidedown through the opposite nozzle 36. The two ends of the strap 29 arethen adjusted until the base 26 is centrally located as desired. Thismay be done by matching an index mark on the strap 29 with the edge ofone of the nozzles 36. The strap 29 is then firmly fastened in place byits buckle 37. Gas from the gas bottle 14 is then allowed to passthrough the valve 23 associated with the inflatable support 26. Thecable 10 is stiffened by inflating its sheath ll in the samernanner, andis then moved through the-sleeve 25 until the first inflatable brace isfree of the top thereof. This can be determined by a scale, not shown,on the cable 10, using the edge of the nozzle 36 as an index means. Thevalve 23 associated with that first inflatable brace 15 is then openedand the gas is allowed toflow until the corresponding flow meterindicates that this brace 15 is fully pressurized. The remaininginflatble braces 15 are inflated in turn as needed, in the same manner.When the .top of the cable 10 has reached the desired height in thecavity the camera 33 may beoriented as desired, horizontally by the stepmotor and vertically by the pneumatic actuator 35. it may .be operatedby the con-. ventional electrical controls 32 (See FIG. 7).

When the inspection is completed, the main valve 23a is closed, thecable1-0 is withdrawn through the sleeve 25, and the inflatable braces 15 aredeflated one by one in reverse order to that of their inflation as theyapproach the sleeve 25. Each valve 23 is equipped with,

a discharge position for this purpose, which opens its correspondingbranch duct to the atmosphere. ,'The base and cable sheath 1] are thendeflated in the same manner, the buckle 37 is unfastened, and theinspection instrument is withdrawn from the rocket motor 31. I

An invention has been described that advances the art of inspectingelongated cavities. Although the preferred embodiments have beendescribed with considerable specificity with regard to detail, it shouldbe understood that many such details may'be altered without departingfrom the scope of the invention as it, is defined in the followingclaims. g

The invention claimed is:

l. A bore inspection instrument comprising:

an inflatable base; I I

means for anchoring the base to some stationary part adjacent the boreto be inspected;

a cable held by the base, capable of sliding motion relative thereto,and including pneumatic tubes;

inflatable braces attached to the cable, each being attached to a tubetherein;

means for controlling fluid flow, attached .to the tubes of the cableand attachable to a source of gas, for controlling inflation of the baseand of the inflatable braces; and

observation means attached to the end of the cable opposite the endattached to a control means.

2. The inspection instrument of claim 1 wherein the base comprises:

a hollow, inflatable cone made of two parallel sheets of thin, flexiblenonelastic material, sealed at their edges, and fibers that extend fromone sheet to the other, the ends of the fibers being embedded in thesheets; and

a curved sleeve fixed in the cone and passing therethrough, one end ofthe sleeve penetrating the top of the cone and the other end extendingfrom the bottom thereof. i v

3. The inspection instrument of claim 1 wherein the observation means isa television camera.

4. The inspection instrument of claim 1 wherein the means forcontrollingfluid flow comprises:

a control box having a threaded cavity for receiving a threaded bottleof compressed gas, and a system of ducts having branch ducts leadingfrom the gas bottle cavity wherein each branch duct is connectable momof the tubes of the cable; and' a valve in each branch duct capable ofopening and closing its duct to the source of gas, and of opening theportion of its duct that lies adjacent'the cable to the atmosphere. 5

5. The inspection instrument of claim eluding: I

a flow meter in eachbranch duct fordetermining when its associatedinflatable device has been inflated', and 1 j a connector for connectingthe branch ducts to the tubes of the cable.

6. The inspection instrument of claim 1 wherein the cable comprisesanoutside sheath and pneumatictubes 4 further ininside the sheath; andwherein the inflatable braces are disks concentric about the cableandattached thereto at 'intervalssuch that the segment of the cable betweenanyftwo adjacentbrace's is resistant to bending.

7. The inspection instrument of claim 6 wherein the inflatable braceshave fibers passing between opposite walls and embedded therein tomaintaindimensional stability thereof when inflated. i i

8. The inspection instrument of claim 6 wherein the sheath of the cableis c'onnectable to'a source of gas and is inflatable, whereby stiffnessmaybe imparted thereto to facilitate its extension into a cavity andwhereby pressure outside and within the pneumatic .tubes maybesubstantially equalized so that their walls may beof minimal thicknessfor compactness when collapsed and folded. 4

9. The inspectioninstrument of claim 8 whereinthe cable includeselectrical conductors connectable at one end to the television camera,and the instrument fun ther includes electrical controls connected toftheelectrical conductors and also connectable toa source of, power. i r

10. An instrument for inspecting elongated cavities tant, and each diskbeing in sealed relationship with comprising: one of the tubes forinflation thereby;

an inflatable base comprising two annular, conical a control box havinga threaded cavity to receive a sheets of thin, flexible, nonelasticmaterial, sealed threaded gas bottle, and having a main duct leading attheir edges, fibers having their ends embedded 5 from the cavity to aplurality of branch ducts; a in the sheets to space them apart when thebase is puncture point in the end of the cavity for opening inflated,and a curbed sleeve fixed in the cone so a gas bottle; a valve in eachbranch duct; a flow that it penetrates the top of the cone and extendsmeter in each branch duct; a valve in the main from the bottom thereof;duct; a connector for connecting each branch duct a strap and fasteningmeans attached to the inflatable 10 to one of the tubes of the cable;and electrical conbase, for anchoring it to some fixed part adjacentductors attachable to a power source and to the the cavity beinginspected; electrical conductors of the cable; and a cable having anouter sheath and tubes and electria television camera on the end of thecable, opposite cal conductors inside the sheath, the cable being thatwhich is attached to the control box, and two held by the base forsliding motion therein; mutually perpendicular step motors attaching thea plurality of inflatable disks fixed concentrically on camera to thiscable end, for orienting the camera.

the cable, being spaced apart so that the segment I of the cable betweenadjacent disks is bend resis-

1. A bore inspection instrument comprising: an inflatable base; meansfor anchoring the base to some stationary part adjacent the bore to beinspected; a cable held by the base, capable of sliding motion relativethereto, and including pneumatic tubes; inflatable braces attacHed tothe cable, each being attached to a tube therein; means for controllingfluid flow, attached to the tubes of the cable and attachable to asource of gas, for controlling inflation of the base and of theinflatable braces; and observation means attached to the end of thecable opposite the end attached to a control means.
 2. The inspectioninstrument of claim 1 wherein the base comprises: a hollow, inflatablecone made of two parallel sheets of thin, flexible nonelastic material,sealed at their edges, and fibers that extend from one sheet to theother, the ends of the fibers being embedded in the sheets; and a curvedsleeve fixed in the cone and passing therethrough, one end of the sleevepenetrating the top of the cone and the other end extending from thebottom thereof.
 3. The inspection instrument of claim 1 wherein theobservation means is a television camera.
 4. The inspection instrumentof claim 1 wherein the means for controlling fluid flow comprises: acontrol box having a threaded cavity for receiving a threaded bottle ofcompressed gas, and a system of ducts having branch ducts leading fromthe gas bottle cavity wherein each branch duct is connectable to one ofthe tubes of the cable; and a valve in each branch duct capable ofopening and closing its duct to the source of gas, and of opening theportion of its duct that lies adjacent the cable to the atmosphere. 5.The inspection instrument of claim 4 further including: a flow meter ineach branch duct for determining when its associated inflatable devicehas been inflated; and a connector for connecting the branch ducts tothe tubes of the cable.
 6. The inspection instrument of claim 1 whereinthe cable comprises an outside sheath and pneumatic tubes inside thesheath; and wherein the inflatable braces are disks concentric about thecable and attached thereto at intervals such that the segment of thecable between any two adjacent braces is resistant to bending.
 7. Theinspection instrument of claim 6 wherein the inflatable braces havefibers passing between opposite walls and embedded therein to maintaindimensional stability thereof when inflated.
 8. The inspectioninstrument of claim 6 wherein the sheath of the cable is connectable toa source of gas and is inflatable, whereby stiffness may be impartedthereto to facilitate its extension into a cavity and whereby pressureoutside and within the pneumatic tubes may be substantially equalized sothat their walls may be of minimal thickness for compactness whencollapsed and folded.
 9. The inspection instrument of claim 8 whereinthe cable includes electrical conductors connectable at one end to thetelevision camera, and the instrument further includes electricalcontrols connected to the electrical conductors and also connectable toa source of power.
 10. An instrument for inspecting elongated cavitiescomprising: an inflatable base comprising two annular, conical sheets ofthin, flexible, nonelastic material, sealed at their edges, fibershaving their ends embedded in the sheets to space them apart when thebase is inflated, and a curbed sleeve fixed in the cone so that itpenetrates the top of the cone and extends from the bottom thereof; astrap and fastening means attached to the inflatable base, for anchoringit to some fixed part adjacent the cavity being inspected; a cablehaving an outer sheath and tubes and electrical conductors inside thesheath, the cable being held by the base for sliding motion therein; aplurality of inflatable disks fixed concentrically on the cable, beingspaced apart so that the segment of the cable between adjacent disks isbend resistant, and each disk being in sealed relationship with one ofthe tubes for inflation thereby; a control box having a threaded cavityto receive a threaded gas bottle, and having a main duct leading fromthe cavity to a plurality of branch ducts; a puncture point in the endof the cavity for opening a gAs bottle; a valve in each branch duct; aflow meter in each branch duct; a valve in the main duct; a connectorfor connecting each branch duct to one of the tubes of the cable; andelectrical conductors attachable to a power source and to the electricalconductors of the cable; and a television camera on the end of thecable, opposite that which is attached to the control box, and twomutually perpendicular step motors attaching the camera to this cableend, for orienting the camera.